The present invention relates to a system and method for intrabody directing and monitoring doses of therapeutic radiation applied to a patient""s body. More particularly, the system and method of the present invention employs an implantable sensor coupled to a relaying device, with which, information pertaining to radiation sensed and optionally quantified by the sensors can be relayed outside the body. In addition, the system and method of the present invention can be utilized to assist in directing radiation to a treatment site within the patient""s body.
Radiation therapy is used extensively in the medical field to treat a variety of medical conditions. Radiation therapy typically utilizes electromagnetic radiation, typically ionizing radiation, such as, but not limited to, x-ray, gamma-rays and particle beams, as well as ultrasonic radiation to treat many types of cancers, tumors and, cell proliferative disorders as well as non-malignant medical conditions, including, but not limited to, the disintegration of stones.
It will be appreciated that radiation is typically detrimental to living cells. It is known that cancerous cells are more prone to the effects of radiation as such cells are rapidly proliferating cells. However, the effect of radiation on normal cells cannot be overlooked. Thus, when treating with radiation, one desires to apply the maximal possible (optimal) dose onto a specific location, trying, as much as possible to avoid radiating neighboring locations, so as to maximize the treatment vs. injury ratio.
Thus, although with some tumors it is possible to take advantage of the higher sensitivity of the tumor cells to the radiative energy, in most radiation therapy procedures localized treatment is effected by incorporating various methods and devices to direct the radiative beams to the site of treatment, so as to enable radiating at optimal therapeutic doses.
It will be appreciated that the precise aiming and collimating of such radiating beam (several centimeters in diameter) onto the treated site is of prime importance in optimizing the healing/injury ratio (see for example U.S. Pat. No. 3,794,840 to Scott and U.S. Pat. No. 4,995,068 to Chou).
However, in spite of such optimization, in the course of treatment, normal cells which surround the tumorous tissue are also effected by the radiation.
In order to minimize the damage to surrounding healthy tissues several dosage monitoring methods have been utilized by oncologists in conjunction with radiation therapy procedures.
One such monitoring method relies on measuring the entrance and exit doses of radiation. Interpolation of this data is used to determine dosage to tissues. However, measurement of entrance and exit doses combined with interpolation can only predict the dosage of the actual entrance and exit locations which are directly measured. In addition, the dosage applied to the treated locations, where interpolation has been performed, cannot always be predicted from the measured entrance and exit doses.
Another monitoring method involves the surgical implantation of thermoluminescent dosimeter (TLD) devices typically inserted through the midplane of the tumor and in single planes above and below the midplane. Unfortunately, such devices are not designed to relay data outside the patient""s body. Thus, not only dosage monitoring is not effected in real time, invasive surgical removal of such devices, under full anesthesia, is required.
Another monitoring method relies on a single skin dose measurement as a checkpoint for the treatment plan. However, this procedure provides the treating physician with very little useful information on the actual dosage delivered deep into the affected tissue and the surrounding body tissues.
Another monitoring method utilized in conjunction with a treatment procedure incorporates a radiation phantom. An example of a radiation phantom is disclosed in U.S. Pat. No. 3,310,885 which describes a radiation phantom for use in a breast irradiation procedure. Such a phantom is fabricated with breast adapters into which TLD devices are inserted, thus, a prescribed radiation treatment is first carried out on the adapter which serves as a control. Although such a system can incorporate many TLD devices and as such, achieve many measurements, the positioning of the adapter, and the size and shape of the adapter is not necessarily repeatable and does not necessarily correspond to the actual positioning, size and shape of the patient""s breast and surrounding tissue. A plastic cup strapped to the patient""s breast has thus been used to shape the breast of the patient to conform somewhat with the phantom breast adapter. In any case, radiation phantoms are localized outside the patient""s body, and as such provide little information, if any, relating to the actual doses applied to the treated site.
Since most of the above mentioned monitoring methods rely heavily on mathematical calculations and projections, such methods fail to accurately predict the doses absorbed by various body regions. Furthermore, since most of these methods employ calculations effected on information retrieved from the dosimetric points, field distortions, which can occur when a radiation beam or beams pass through an organ or tissue are not accounted for.
As such when monitoring is not effected directly in the tumor but rather on the skin, or on an extracorporeal phantom such as with the methods described above, the accurate prediction of dosage to the tumor itself ad to surrounding healthy tissues is not possible.
To try and overcome the limitation inherent to these dosage monitoring methods and as such to try and minimize the damage caused to surrounding healthy tissues while maintaining effective radiation procedure, oncologist often resort to the implantation of radio-opaque metal clips at the tumor boundaries, which can be viewed by a fluoroscope, and as such assist the oncologist to pinpoint the radiation beam.
This method has very poor resolution, does not yield the dose locally absorbed by any specified organ and does not enable a closed loop control of the radiation conditions.
A more precise method for monitoring dosage at a specific treatment site is termed brachytherapy and involves surgically locating a radioactive source in the specific treatment site. Examples of brachytherpy include the implantation of radioactive capsules for a short time period into the cancerous prostate, breast, or brain. Such radioactive capsules are removed following the radiation therapy procedure. There is no control over the local dose and zone of radiation and only remote sensors and indirect calculations are used in order to provide information about the physical properties monitored, as such, the physician has to decide upon the success or damage of the treatment using semi-accurate data. Also, to obtain satisfactory clinical results, such as necrosis of the tumor, a very precise administration of the radioactive source should be kept.
To further increase the accuracy of the irradiation treatment and as such to minimize the damage inflicted upon surrounding healthy tissues several and more advanced systems and methods are utilized.
In treating some cell proliferative disorders it is possible to utilize a microsurgical spot-like radiation beam. This irradiation method allows the oncologist to precisely irradiate small and specific body sections formerly treated by brachytherapy or surgery. One such procedure incorporates what is known in the art as a gamma knife which can be operated on a tumor (in the brain for example), a blood vessel, (such as a coronary artery) where it helps in preventing cell proliferation and restenosis following balloon, stent or graft angioplasty. In a gamma knife procedure, a plurality of gamma radiation beams are directed so as to cross one another at the treatment site, so as to increase the radiative dose thereat, while, at the same time, to reduce the damage to surrounding tissues.
Yet another irradiation procedure which is used for the extermination of malignant cells of a cancerous tumor employs a highly focused microwave beam. An abnormally enlarged or cancerous prostate, breast tumors and some types brain cancer qualify for this type of treatment. The desired destruction is achieved by thermalablation or hyperthermia of the relevant tissue (see, for example, U.S. Pat. No. 5,807,395 to Peter Mulier).
Both the gamma knife and the highly focused microwave beam procedures are advantageous in being non-invasive, but control measurements must be employed against tissue overheating, overexposure or deviation of the beam(s) which may result in damage to the surrounding healthy tissues. In addition, while using microwave radiation a secondary effect caused by the tissue heating resultant from the procedure is a structural modification of the tissue which can lead to a change of the path previously set for the therapeutic radiation.
Although x-ray fluoroscopy is used in combination with these procedures to direct the physician to the site of treatment, this method is limited to stationary treatment sites and as such the application of a gamma knife or a highly focused microwave beam to a treatment site of moving organs such as a pulsating heart cannot be easily effected with accuracy.
In a limited number of medical procedures which incorporate stent or grafts a radioactive source can be incorporated into the stent or graft to effect treatment. Such a radioactive stent or graft typically has a short radiation half-life period which is comparable with the time period corresponding to the cell proliferation stage. Such a device is, therefore, usable only for a very short time period and has a very short shelf life before use. In most cases, it is generally necessary to supplement this procedure with an invasive guide wire catheter procedure which employs a radioactive distal end and inserted within the body for several hours. Moreover, the implantation of a radioactive stent or graft requires both an oncologist and a cardiologist to be present at the time of the procedure further complicating matters.
Thus, there exists no efficient system or method with which a physician can precisely direct a radiation dose of any radiation type to a treatment site and/or monitor with accuracy the radiative dosages absorbed by both the treatment site and the tissue which surrounds the treatment site.
There is thus a widely recognized need for, and it would be highly advantageous to have, a system and method for directing and monitoring a therapeutic radiation dose within a patient""s body devoid of the above limitations.
According to one aspect of the present invention there is provided a system for use in a medical procedure, the medical procedure utilizes radiation for irradiating a specific region of a patient""s body, the system comprising (a) at least one sensor being implantable within, or in proximity to, the specific region of the patient""s body, the at least one sensor being for sensing at least one parameter associated with the radiation; and (b) a relaying device being in communication with the at least one sensor, the relaying device being for relaying information pertaining to the at least one parameter and therefore to the radiation outside of the patient""s body.
According to further features in preferred embodiments of the invention described below, the system further comprising an extracorporeal monitoring unit communicating with the at least one sensor via the relaying device, the relaying device including wires wirable between the at least one sensor and the extracorporeal monitoring unit.
According to still further features in the described preferred embodiments the relaying device further includes a processor communicating with the at least one sensor.
According to still further features in the described preferred embodiments the processor is intrabody transplantable.
According to still further features in the described preferred embodiments the processor is extracorporeal
According to still further features in the described preferred embodiments the relaying device is an implantable telemetry device.
According to still further features in the described preferred embodiments the implantable telemetry device includes a processor communicating with the at least one sensor.
According to still further features in the described preferred embodiments the system further comprising an extracorporeal monitoring unit telemetrically communicating with the at least one sensor via the implantable telemetry device.
According to still further features in the described preferred embodiments the system further comprising an extracorporeal monitoring unit telemetrically bidirectionally communicating with the transducer unit via the interrogating signal and the signal receivable outside the body.
According to still further features in the described preferred embodiments the at least one sensor is battery powered and further wherein the relaying device includes a transmitter for relaying information pertaining to the at least one sensor outside the body.
According to still further features in the described preferred embodiments the extracorporeal monitoring unit includes a radiation control feedback element, the radiation control feedback element communicating with a source of the radiation for directing the radiation in a desired direction relative to the at least one sensor.
According to still further features in the described preferred embodiments the extracorporeal monitoring unit includes a radiation dose control feedback element, the radiation dose control feedback element communicating with a source of the radiation for controlling a radiation dose applied to the specific region of the patient""s body
According to still further features in the described preferred embodiments and as further detailed hereinunder, the at least one sensor is integrated into a stent or graft.
According to another aspect of the present invention, in a medical procedure utilizing radiation for irradiating a specific region of a patient""s body, there is provided a method of monitoring the radiation comprising the steps of (a) implanting at least one sensor within, or in proximity to, the specific region of the patient""s body, the at least one sensor being for sensing at least one parameter associated with the radiation; and (b) relaying outside the patient""s body, during the course of the procedure, information pertaining to the at least one parameter.
According to yet another aspect of the present invention, in a medical procedure utilizing radiation for irradiating a specific region of a patient""s body, there is provided a method of directing the radiation relative to the specific region of the patient""s body, the method comprising the steps of (a) implanting at least one sensor within, or in proximity to, the specific region of the patient""s body, the at least one sensor being for sensing at least one parameter associated with the radiation; and (b) providing outside the body a radiation control feedback element communicating with a source of the radiation and with the at least one sensor, the radiation control feedback element serves for directing the radiation in a desired direction relative to the specific region of the patient""s body; and (c) relaying, during the course of the procedure, information pertaining to the at least one parameter from the at least one sensor to the radiation control feedback element for effecting the step of directing the radiation in a desired direction relative to the specific region of the patient""s body.
According to still another aspect of the present invention, in a medical procedure utilizing radiation for irradiating a specific region of a patient""s body, there is provided, a method of controlling a dose of radiation applied to the specific region of the patient""s body, the method comprising the steps of (a) implanting at least one sensor within, or in proximity to, the specific region of the patient""s body, the at least one sensor being for sensing at least one parameter associated with the radiation; (b) providing outside the body a radiation control feedback element communicating with a source of the radiation and with the at least one sensor, the radiation control feedback element serves for controlling the dose of radiation being applied to the specific region of the patient""s body; and (c) relaying, during the course of the procedure, information pertaining to the at least one parameter from the at least one sensor to the radiation control feedback element for effecting the step of controlling the dose of radiation being applied to the specific region of the patient""s body.
According to further features in preferred embodiments of the invention described below, the radiation is provided via a radiation source from either the inside or the outside of the patient""s body.
According to still further features in the described preferred embodiments the radiation is a light beam provided from inside the patient""s body.
According to still further features in the described preferred embodiments the method further comprising the step of processing the information via a processor.
According to still further features in the described preferred embodiments each of the at least one sensor has an identification code associated therewith for identifying each of the at least one sensor.
According to still further features in the described preferred embodiments the step of relaying outside the patient""s body, during the course of the procedure, the information pertaining to the at least one parameter is effected by an implantable telemetry device.
According to still further features in the described preferred embodiments the implantable telemetry device includes a processor communicating with the at least one sensor, the processor serves for processing the information.
According to still further features in the described preferred embodiments the step of relaying outside the patient""s body, during the course of the procedure, the information pertaining to the at least one parameter is further effected by an extracorporeal monitoring unit communicating with the at least one sensor via the implantable telemetry device.
According to still further features in the described preferred embodiments the implantable telemetry device includes a transducer unit designed for transducing an interrogating signal receivable from outside the body into a first electrical signal for powering the at least one sensor and for receiving a second electrical signal from the at least one sensor, transducing the second signal into a signal receivable outside the body, such that the information pertaining to the at least one parameter is relayable outside the patient""s body following the generation of the interrogating signal.
According to still further features in the described preferred embodiments the transducer unit is an acoustic transducer unit, the interrogating signal is an acoustic interrogating signal, and the signal receivable outside the body is an acoustic signal.
According to still further features in the described preferred embodiments the acoustic transducer unit includes (i) a cell member having a cavity; (ii) a substantially flexible piezoelectric layer attached to the cell member, the piezoelectric layer having an external surface and an internal surface, the piezoelectric layer featuring such dimensions so as to enable fluctuations thereof at its resonance frequency upon impinging of an external acoustic wave; and (iii) a first electrode attached to the external surface and a second electrode attached to the internal surface.
According to still further features in the described preferred embodiments the transducer unit is a radio transducer unit, the interrogating signal is a radio interrogating signal, and the signal receivable outside the body is a radio signal.
According to still further features in the described preferred embodiments the at least one sensor and the radio transducer unit are intrabodily wired so as to enable transplanting the radio transducer unit close to the skin, while at the same time transplanting the at least one sensor deeper within the body of the patient.
According to still further features in the described preferred embodiments the interrogating signal is generated by, and the signal receivable outside the body is received by, an extracorporeal monitoring unit telemetrically bidirectionally communicating with the transducer unit.
According to still further features in the described preferred embodiments the medical procedure is selected from the group consisting of gamma knife microsurgery, thrombolysis, stones disintegration, thermalablation and extermination of benign and malignant tumor masses.
According to still further features in the described preferred embodiments the radiation is selected from the group consisting of an ultrasonic radiation and electromagnetic (both nuclear, i.e., ionizing, and wave, e.g., non-ionizing and ionizing) radiation.
According to still further features in the described preferred embodiments the electromagnetic radiation is selected from the group consisting of alpha radiation, beta radiation, gamma radiation, X-ray radiation and neutron radiation.
According to still further features in the described preferred embodiments the electromagnetic radiation is selected from the group consisting of microwave radiation and visible light radiation, ultraviolet radiation and infrared radiation (e.g., near, medium and far infrared).
According to still further features in the described preferred embodiments the medical procedure is employed for treating a medical disorder characterized by abnormal cell proliferation.
According to still further features in the described preferred embodiments the medical disorder is selected from the group consisting of a tumor, a cancer, a thrombus and restenosis.
According to still further features in the described preferred embodiments the at least one sensor is selected from the group consisting of a temperature sensor, such as a thermocouple or thermistor, an electromagnetic radiation sensor, such as a solid-state diode or a scintillating crystal, an acoustic radiation sensor, such as a hydrophone, a light sensor, such as a photodiode and an electromagnetic field sensor, such as a coil.
According to still further features in the described preferred embodiments the at least one parameter is directly associated with the radiation, thereby the at least one sensor directly senses the radiation.
According to still further features in the described preferred embodiments the at least one parameter is indirectly associated with the radiation, thereby the at least one sensor indirectly senses an interaction of the radiation with the body.
According to still further features in the described preferred embodiments the at least one sensor is selected from the group consisting of a scintillation crystal sensor and a solid state semi-conductor sensor.
According to still further features. in the described preferred embodiments the step of relaying outside the patient""s body, during the course of the procedure, the information pertaining to the at least one parameter is effected by a transmitter.
According to an additional aspect of the present invention there is provided an implantable stent or graft system for monitoring, directing and/or dosing radiation applied to a specific region of a patient""s body, the stent or graft system comprising (a) a stent or a graft element; (b) at least one sensor being attached to the stent or graft element, the at least one sensor being for sensing at least one parameter associated with the radiation; and (c) a telemetry device being attached to the stent or graft element and being in communication with the at least one sensor, the telemetry device being for relaying the information outside of the patient""s body.
According to further features in preferred embodiments of the invention described below, the stent or graft is a vascular stent or graft.
According to still further features in the described preferred embodiments the telemetry device is an acoustic telemetry device.
According to still further features in the described preferred embodiments the telemetry device is a radio frequency telemetry device.
According to still further features in the described preferred embodiments the radiation is selected from the group consisting of an ultrasonic radiation and electromagnetic radiation.
According to still further features in the described preferred embodiments the electromagnetic radiation is selected from the group consisting of alpha radiation, beta radiation, gamma radiation, X-ray radiation and neutron radiation.
According to still further features in the described preferred embodiments the at least one sensor is within a wall of the stent or graft element.
According to still further features in the described preferred embodiments the telemetry device is within a wall of the stent or graft element.
According to still further features in the described preferred embodiments the at least one sensor is externally attached to a wall of the stent or graft element.
According to still further features in the described preferred embodiments the telemetry device is externally attached to a wall of the stent or graft element.
According to still further features in the described preferred embodiments the at least one sensor is internally attached to a wall of the stent or graft element.
According to still further features in the described preferred embodiments the telemetry device is internally attached to a wall of the stent or graft element.
The present invention successfully addresses the shortcomings of the presently known configurations by providing a system and method which relays, during a radiation procedure, information related to the radiation from within the body to the outside. Such information is used according to preferred embodiments of the invention to monitor the radiation and to control its dose and/or direction.